Streets and Highways Code § 22175
CHAPTER 7. Sale and Redemption of Delinquent Property
The applicant for a deed shall file with the tax collector an affidavit or affidavits showing that notice of the application has been given, and if the notice was not served personally on the owner of the property, that due diligence was used to find the owner. The tax collector shall file the affidavit or affidavits in his office.